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"Worker" and "slacker" rats show differences in decision-making processes

A team of researchers led by Dr. Catharine Winstanley has identified differences in the brains of rats engaged in decision-making processes, revealing individual variability in cognitive effort and motivation and confirming that there is no one central decision-making region in the brain.

Many psychiatric disorders are associated with defects in decision-making, including bipolar disorder, psychopathy, drug and gambling addiction, and suicidal ideation. Understanding the mechanisms underlying the decision-making process is a promising step toward identifcation of new targets of intervention in these disorders.

These results were presented at the 2018 Canadian Neuroscience Meeting in Vancouver today.

Dr. Winstanley and her team engaged rats in a cognitive effort task in which the animals learn to earn treats by poking their noses into one of five response holes when a light inside one of the holes is illuminated.

Rats were given the option of pressing one of two levers. One lever corresponded with a reliably easy task, where the light flashed for one second, and offered a reward of one sugar pellet. The second lever corresponded with a task requiring more attention, where the light shone for only 0.2 seconds, but resulted in a reward of two sugar pellets.

The team found that some rats—"the slackers"—prefered the easier task, while others—the "workers"—prefered the more challenging task and its associated rewards. Interestingly, they found that individual choice did not correlate with the rat's ability to complete the task, or the efficiency with which it could accomplish it.

"Our research shows that decision-making relies on brain regions involved in emotional responses, and translating those emotions into actions, but also on regions in the frontal cortex which are involved in detecting causal relationships between events and evaluating outcomes," said Dr. Winstanley. "We've shown that there is not a simple decision-making center in the brain, but rather that many brain regions and systems work together to integrate information in order to quantify information about risk, reward and effort required, resulting in how a decision is made."

In healthy humans, the ability to choose an option that may be more diffcult but may lead to a higher reward in the long term can have important benefits for individuals.

"The degree to which we are willing to select options that require more cognitive effort but that have the potential to lead to greater rewards has far-reaching consequences for our economic and personal success," said Dr. Winstanley. "Understanding how the brain facilitates decision-making is one of the most fundamental pursuits in neuroscience today."